Measurement apparatus including zero setting means

ABSTRACT

The present invention relates to a measurement device, particularly of electrical units, which includes a fixed measurement part and a mobile assembly, the whole of which forming the measurement components properly so called, the mobile assembly being fitted with a rotatable axle held in position and guided close to its tips, a needle and at least one release spring on said rotating axle.

United States Patent Inventors Appl. No.

Jacques Paleucber; Michel Penand, both of Troyes, France 8 1 1,897

Filed Patented Assignee Apr. 1, 1969 Aug. 10,1971 Lebpcey Industries Troyes, France Priority France Apr. 11, 1968, Mar. 17, 1969 1572361 and 6907560 MEASUREMENT APPARATUS INCLUDING ZERO SETTING MEANS 6 Claims, 13 Drawing Figs.

US. Cl .1 324/154 Int. G0lr1/00 Field of Search 324/ 154,

Primary Examiner-Alfred E. Smith Attorney-McNenny, F arrington, Pearne and Gordon ABSTRACT: The present invention relates to a measurement device, particularly of electrical units, which includes a fixed measurement part and a mobile assembly, the whole of which forming the measurement components properly so called, the mobile assembly being fitted with a rotatable axle held in position and guided close to its tips, a needle and at least one release spring on said rotating axle.

PATENTEUAUBIOIQR 7 3,599.09.

SHEET 3 [IF 7 MEASUREMENT APPARATUS INCLUDING ZERO SETTING MEANS The invention relates to a measurement device comprising a mobile assembly, a rotating axle for the mobile assembly, means close to both tips of the rotating axle intended for holding and guiding the axle, a needle secured to said axle and a spiral spring linked by one of its tips to this axle, the device also comprising a bearing coaxial with the rotating axle and an assembly swiveling on the coaxial bearing, said swiveling assembly nesting the free end of a release spring.

The invention relates to a measurement device shown as a nonrestrictive example on the attached drawings, wherein:

FIG. 1 is an axial cross section view of the device according to the invention;

FIG. 2 is a view of FIG. I from the left side;

FIG. 3 is a cross section along A-r-A of FIG. 2;

FIG. 4 is a top viewof the part nesting the outer end of the release spring;

FIG. 5 is a diagram cross section showing another embodiment of the axial bearing of the axis of the device;

FIG. 6 is another view showing the bearing assembly of FIG.

FIGS. 7 and 8 show other bearings for the lower end of the axle of the device;

FIG. 9 shows one means for obtaining the damping of the axle of the device;

FIG. 10 is a vertical cross section along an axis, showing another embodiment of the measurement device;

FIG. 1 l is a cross section along 8-8 of FIG. 10;

FIG. 12 is a top view of FIG. 10;

FIG. 13 is a fractional view of the framing.

The measurement device shown on FIG. 1 comprises a needle l which revolves above and around a scale held by plate 2, and a solenoid 3 formed of a coil supported by parts 4 and 5.

In this coil is housed a plug 6 which is provided with lateral and axial guiding means of axle.7 of the measurement device.

Said axle 7 includes a small blade 11 which moves in front of a segment 12 of a cylinder made of ferromagnetic material which is secured to the inner part of plug 6.

Said cylinder segment 12 bears a radial rim at one of its ends so as to produce, as one knows, an electric current proportional to the magnitude of the voltage applied to solenoid 3 between this segment 12 of cylinder and small blade 11.

The lower end of axle 7 is thinned down or conically shaped for instance and bears on the flat surface 8, of a part 9 made of a plastic material.

Said part 9 of plastic material is fitted in plug 6 and is not adjustable in the axial direction. It also supports a second part 10 made of plastic material.

Flat surface 8, which supports thinned down end 7,, serves thereby as lower support for axle 7, while part 10 includes a close clearance bore 10, for the lateral guiding of the axle 7.

This type of assembly provides an extremely low drag to the rotating of axle 7, owing to the separation of the axial guiding means obtained with flat surface 8,, from lateral guiding, secured by bore 10, in part I0 which is very thin in an axial direction.

Plug 6 houses at its open end a rotatable plastic part 13, which comprises ribbed segments on its lower part, four ribs for instance, which, owing to the flexibility of plastic material, are seated through their ribs or flanges 14,, into a circular groove 6, of plug 6 (see FIGS. .1, and 3).

This setting thereby providesthe holding of part 13 into the plug 6, while allowing it to rotate.

This part 13 also includes a projecting conical segment 15, having a bore 15 therethrough, said bore 15 having a conical shape or any other geometrical shape, which tends to cut down as far as possible the friction between the axle and the part 13. Said part 13 is ended by a conical segment 15,, against which is eventually placed a washer 16 fitted on axle 7 so as to fix axially said axle.

Needle l is fitted on axle 7 by means of a split ring 18 fastened to axle 7 and which holds the inner tip of a spiral release spring 19.

The outer tip of the spiral spring 19 is set into the slot 20, of part 20 (FIG. 4) placed over part;13, so as to allow the adjustment of the spring 19 by moving said part 20 in one direction or in another. Part 20, which allows the initial adjustment of the device, moves concentrically about the axis of the device, or along any other way which will allow such adjustment.

This constitutes an internal adjustment of the device which 1 is carried out when the device is being assembled.

The setting above described allows therefor e resetting of needle 1 close to the zero of the scale of the dial, which, in the case of a mobile assembly device, runs in connection with a stop 21 or 22 on one of the bearings according to the direction of the deviation and to the relative position of point zero (left or right).

According to the invention, there'is also a second system for the adjustment of point zero of the device; said system can be operated from the outer part of the device which allows adjustment at any time by the user.

This adjustment is obtained by rotation of part 13, which, as already explained, is secured to the outer end of spiral spring 19 through part 20;

Said part 13 includes an extension including a slot 23, nesting a teat 24 of button 25, held by its head 26, on the front side 27 of the device.

Said teat 24 is eccentrically located on button 25, thereby when being rotated in a way or in another, causes ribs 14, of part 13 to swivel into the corresponding groove 6, of plug 6.

It appears, as a consequence, that according to this assembly process, part 13 allows lateral guiding of axle 7 through bore 15, the axial guiding of this axle through its side 15,, the holding of inner adjustment means of point zero through part 20 as well as the adjustment of point zero of the device through outer means by the use of head 26 of button 25.

Said part 13 is made of a plastic material, distortable enough so as to allow the disposition of ribs 14, into groove 6, by a mere elastic distortion, causing thereby parts 13 and 6 to interlock; the parts 13 and 6 are in turn fitted with a part 4 made of a plastic material, the elastic distortions of which allow the interlocking within grooves 6 (FIG. 3).

According to another embodiment and in order to lessen friction of washer 16 on conical part 15,, said bearing is placed on a part 13, in an upper bridge position (see FIGS. 5 and 6), and the end 7, (round or sharp) of axle 7 bears on this part 13,.

Part 13, is made of a plastic material and is interlocked with part 13 which is also made of plastic material.

In the embodiment shown by FIG. 1, damping can be obtained with oil stored in cavity 9, (see FIG. 7) in housing 9.

According to another embodiment of a lower pivot (see FIG. 8, the guiding and the rotating functions are carried out exclusively by a part 9, the inner part of which is conically shaped to seat the point end of axle 7. In this case, a washer 10, allowing a clearance at point 10,, is provided to retain damping oil. Said clearance is so set as to prevent axle 7 from bearing on part 10, and to ensure the retaining of oil in cavity 9, of housing 9.

According to another embodiment of the damping system, (FIG. 9), friction coefficients between the axle 7 and the damping material (oil, for instance) are increased by adding a small blade 7,, on axle 7. This modification provides a better damping for an oil having a given viscosity, or allows the use of an oil having a lower viscosity to obtain a given damping.

Small blade 7 is made of plastic material as well as sleeve 7,, thereby allowing the assembly of unit 7 7., by a mere tight fitting on axle 7.

FIGS. 10 to 13 show another embodiment of the device according to the invention: this device comprises, under a dial 31, a casing 32 secured thereto by means of screws 33.

Above dial 31 there is positioned a mask 34, partially or entirely transparent, through which measuring needle 35 (FIG. 11) can be seen moving in front of a calibrated scale (not shown).

The measurement unit forms a compact block and the assembly of the various components thereof is made with a frame of plastic material 36 which is secured to the bottom part of the casing 32 by screws 37.

Frame 36 is made of two parts 36 and 36 which are assembled by frictionally gripping tongues 38 extending into grooves 38a.

Parts 36,, 36 so nested, are made in such way as part 36 forms the main part of the frame while part 36 forms only an upper attaching lug.

On both of vertical legs of part 36, of the frame are slots or recesses 36, in which is fitted a sleeve 39, said sleeve being further held in position at its upper extremity by flanges 36 of frame part 36,.

Along the axis of both parts 36,, 36 of the frame there are provided cylindrical bearings 40 and 41 to which handle 42 and 43 are frictionally secured and which are intended for the adjustment of the resetting at the zero point and to the release of needle 35 at its initial position. Handle 43 allows the provision of a measurement device the zero point of which is in the center of the dial.

In the axis of these cylindrical bearings there are provided conical seats 44 which receive the conical tips of axle segments 45.

Said axle segments 45, are arranged in axial alignment to define the axis of rotation of the mobile assembly. The main bearing is formed of a plastic frame 46 having a U-shaped cross section. On'the inner wall of said frame 46 there is provided a metallic frame, made of copper or of aluminum which is intended to improve the damping of the device. At the inner part of the U of frame 46 there is provided a measurement solenoid 48.

The frame comprises ribs 49 set at diametrically opposite positions inside which are held small plates 50 serving to support axle segments 45 through the collars or hubs 51 supporting spiral springs 52 and 53.

The hubs 51 receive and retain the inner tips of spiral springs 52, S3.

Outer tips of springs 52 and 53 are respectively secured to handles 42 and 43 (FIG. 11) allowing thereby the adjustment of said springs 52 and 53 and, consequently the zero point of the device.

Handle 43 can not be reached from the outside of the device when the measurement unit is housed in casing 32.

The handle 43 therefore serves for the initial adjustment of the device while being assembled.

On the other hand, handle 42 bears at its tip a fork 42 inside which is positioned the catch-pin 54 of a button 54 which can be reached on the cover 34 of the measurement device.

Thus, when revolving button 54 with a screw driver or any similar tool, catch-pin 54 is moved, which causes a change of the angular position of handle 42 and thereby modifies the tensile strength of upper spring 52 which allows a resetting at the zero point.

Handles 42 and 43, as well as central parts 51 are made of plastic material; wires 55 are welded to outer tips of spirals 52 and 53, said tips being secured to handles 42 and 43 by gluing in the grooves cut or formed therein.

Furthermore, both of hubs 51, arranged in opposite position on frame 49 are secured to the ends of the measurement solenoid 48 and said solenoid 48 is therefore connected to the source to be measured through wires 55 which penetrate through the casing 34 and ending at each of handles 43 and 42.

The fixed part of the measurement unit is formed of a magnet 56, in the example shown in FIG. 10 which is secured to frame 36, on the one hand by ribs 57 formed on part 36 of the frame, and on the other hand, by axially extending bearings 58 formed on part 36 In this device, all those parts which do not serve to the measurement or the conveyance of power are made of plastic material so as to provide a simple and sturdy construction as well as an easy assembly. Owing to this type of construction, parts 36,, 36 of the frame holding the fixed magnet and the mobile assembly can be fitted together by a mere press fitting.

It should be remarked that, in this design, the frame holds by itself the whole of the fixed and mobile parts serving to the measurement as well as the measurement needle and the release device.

Furthermore, it should be remarked that, at the time parts 36, and 36, are fitted together, the magnet and the mobile assembly are set in position one with respect to the other and with respect to the frame (frame 46, rotating units 47, 48, needle 35, axle segments 45,) electrical energy feeding means of the measuring apparatus, i.e., electrical conductors 55 which are connected to the external extremities of springs 52 and 53,

etc.

The invention, of course, is not restricted to the embodiments hereinabove shown and described, from which various other embodiments may be envisaged, such changes being considered as coming within the scope of the invention.

We claim:

1. A measuring instrument including a frame, a mobile assembly, a rotatable axle for said mobile assembly, means coacting between the frame and mobile assembly adjacent both tips of the rotating axle for guiding and holding said axle, a needle secured to said axle, and a spiral spring linked by one of its tips to said axle, said frame including a plug member coaxial with the rotatable axle and an adjustment assembly selectively rotatable on said coaxial plug member, said adjustment assembly holding the other end of said spiral spring.

2. An instrument in accordance with claim 1 in which the plug member is closed at one end and includes at its open end a peripheral groove, and said adjustment assembly includes radially projecting ribs resiliently interlocked in said groove whereby axial movement of said adjustment assembly is prevented.

3. An instrument in accordance with claim 1 wherein the plug member includes at its closed end a bearing body including a flat surface against which one end of said rotating axle bears and lateral guiding means spaced therefrom in an axial direction comprising a close clearance collar surrounding said axle to limit axial movement thereof.

4. An instrument in accordance with claim 1 wherein the adjustment assembly adjacent the open end of said plug member includes a projection having an axial bore for supporting the opposite end of said rotatable axle.

5. An instrument in accordance with claim 1 wherein the frame includes a U-shaped member and a cap member resiliently interlocked together to form a closed frame.

6. An instrument in accordance with claim 5 in which the cap member includes a cylindrically shaped inwardly projecting bearing member, the adjustment assembly being rotatably mounted thereon. 

1. A measuring instrument including a frame, a mobile assembly, a rotatable axle for said mobile assembly, means coacting between the frame and mobile assembly adjacent both tips of the rotating axle for guiding and holding said axle, a needle secured to said axle, and a spiral spring linked by one of its tips to said axle, said frame including a plug member coaxial with the rotatable axle and an adjustment assembly selectively rotatable on said coaxial plug member, said adjustment assembly holding the other end of said spiral spring.
 2. An instrument in accordance with claim 1 in which the plug member is closed at one end and includes at its open end a peripheral groove, and said adjustment assembly includes radially projecting ribs resiliently interlocked in said groove whereby axial movement of said adjustment assembly is prevented.
 3. An instrument in accordance with claim 1 wherein the plug member includes at its closed end a bearing body including a flat surface against which one end of said rotating axle bears and lateral guiding means spaced therefrom in an axial direction comprising a close clearance collar surrounding said axle to limit axial movement thereof.
 4. An instrument in accordance with claim 1 wherein the adjustment assembly adjacent the open end of said plug member includes a projection having an axial bore for supporting the opposite end of said rotatable axle.
 5. An instrument in accordance with claim 1 wherein the frame includes a U-shaped member and a cap member resiliently interlocked together to form a closed frame.
 6. An instrument in accordance with claim 5 in which The cap member includes a cylindrically shaped inwardly projecting bearing member, the adjustment assembly being rotatably mounted thereon. 